Hello All, I have two different internet facing cas locations (Exchange 2010 SP2) and want to use a single global url (mail.domain.com) to access mailbox. I need to setup InternalURL and ExternalURL values for both CAS server location. I have idea as below but not sure will it work?? External DNS ISP 1 IP Address ISP 1 IP Address Host (A) mail.domain.com 202.1.1.1 mail.domain.com 303.1.1.1 Host (A) mail1.domain.com 202.1.1.1 mail2.domain.com 303.1.1.1 Internal DNS AD Site SiteA SiteB NLB Name noidanlb.domain.com 10.0.0.1 pthnlb.domain.com 20.0.0.1 CAS-InternalURL mail.domain.com 10.0.0.1 mail.domain.com 20.0.0.1 CAS-ExternalURL mail1.domain.com 10.0.0.1 mail2.domain.com 20.0.0.1 UserA with mailbox UserB with mailbox Case1: WAN link UP between SiteA and SiteB 1.In this case if userA access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteB, will userA redirect to SiteA for mailbox. 2. Similarly if userB access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteA, will userB redirect to SiteA for mailbox. Case2: WAN link DOWN between SiteA and SiteB 1.In this case if userA access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteB, will userA redirect to SiteA for mailbox. 2. Similarly if userB access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteA, will userB redirect to SiteA for mailbox. Thanks in advance NKumar

"Proxying requests between two Exchange 2010 Client Access servers enables organizations that have multiple Active Directory sites to designate one Client Access server as an Internet-facing server and have that server proxy requests to Client Access servers in sites that have no Internet presence." "Outlook Web App users who access an Internet-facing Client Access server in a different Active Directory site than the site that contains their mailbox can be redirected to the Client Access server in the same site as their Mailbox server if that Client Access server is Internet facing." "when a Client Access server receives a request for a user whose mailbox is in an Active Directory site other than the one the Client Access server belongs to, it looks for the presence of an ExternalURL property on the relevant virtual directory on a Client Access server that's in the same Active Directory site as the user's mailbox. If the ExternalURL property exists, and the client type supports redirection (for example, Outlook Web App or Exchange ActiveSync), the Client Access server will issue a redirect to that client. If there's no ExternalURL property present, or if the client type doesn't support redirection (for example, POP3 or IMAP4), the Client Access server will try to proxy the connection to the target Active Directory site." ----- Understanding Proxying and Redirection Whether the user will be redirected or proxied, it's decided by the ExternalURL and Internet presence. So the key is how do you set the ExternalURL of your CAS servers. In the case, I suppose you should set ExternalURL as mail1.domain.com and mail2.domain.com, and they should be public on the internet. I think you can get more detail information in above link.Jack Zhou

"Proxying requests between two Exchange 2010 Client Access servers enables organizations that have multiple Active Directory sites to designate one Client Access server as an Internet-facing server and have that server proxy requests to Client Access servers in sites that have no Internet presence." "Outlook Web App users who access an Internet-facing Client Access server in a different Active Directory site than the site that contains their mailbox can be redirected to the Client Access server in the same site as their Mailbox server if that Client Access server is Internet facing." "when a Client Access server receives a request for a user whose mailbox is in an Active Directory site other than the one the Client Access server belongs to, it looks for the presence of an ExternalURL property on the relevant virtual directory on a Client Access server that's in the same Active Directory site as the user's mailbox. If the ExternalURL property exists, and the client type supports redirection (for example, Outlook Web App or Exchange ActiveSync), the Client Access server will issue a redirect to that client. If there's no ExternalURL property present, or if the client type doesn't support redirection (for example, POP3 or IMAP4), the Client Access server will try to proxy the connection to the target Active Directory site." ----- Understanding Proxying and Redirection Whether the user will be redirected or proxied, it's decided by the ExternalURL and Internet presence. So the key is how do you set the ExternalURL of your CAS servers. In the case, I suppose you should set ExternalURL as mail1.domain.com and mail2.domain.com, and they should be public on the internet. I think you can get more detail information in above link.Jack Zhou

Hi NKumar, Any other question?Jack Zhou

Hi NKumar, Any other question?Jack Zhou